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Physiology Exam 1 Study

Chapter 6 Communication & homeostasis

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What are the two basic physiological signals?

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-Chemical -Electrical

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What are the basic methods of cell-cell communication?

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- Direct cytoplasmic transfer- Gap junctions- Contact-dependent signals- Local communication- Long distance communication

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Which method of cell-to-cell communication occurs by chemicals that diffuse through the extracellular fluid?

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-Local Communication

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This method of cell-to-cell communication involves the transfer of chemical and electrical signals between adjacent cells.

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-Gap junctions

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Where would you expect to find Gap Junctions in the body?

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-Heart-Smooth muscle of the GI tract

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What are the cells that receive electrical or chemical signals called?

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-Target Cells

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What is the simplest form of cell-to-cell communication?

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-Gap junctions

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A gap junction forms from the union of membrane-spanning proteins called____.

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-Connexon

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When do connected cells function like a synctium?

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-When the gap junction (connexon) is open.

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What is the only means by which electrical signals can pass directly from cell to cell?

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-Gap junctions

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What method of cell-to-cell communication utilize Cell Adhesion Molecules (CAMs) to transfer signals?

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-Contact Dependent

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How is local cell-to-cell communication accomplished?

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-Paracrine signaling-Autocrine signaling

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If a chemical signal acts on the cell that secreted it, it is called an _____ signal.

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-Autocrine

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If a chemical acts on cells in the immediate vicinity of the cell that secreted it, its is called ____ signal.

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-Paracrine

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If a cell secretes chemicals that act on distal cells it is a ____ signal.

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-Endocrine

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What is secreted by neurons to act on itself or neighboring cells?

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-Neuromodulators

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What are regulatory substances that mediate immune responses?

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-Cytokines

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Why are paracrine and autocrine signals only able to reach adjacent cells?

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-Because both of these signals reach their targets by diffusing through the interstitial fluid. Diffusion is limited by distance.

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Most long-distance communication between cells is the responsibility of what two organ systems?

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-Nervous system-Endocrine system

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An electrical signal travels along a ___ until it reaches the very end of the cell, where it is translated into a ____ .

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Neuron,Neurocrine

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If a neurocrine diffuses into the blood it is called a ____.

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Neurohormone

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If a neurocrine acts more slowly as an autocrine or paracrine signal, it is called a ______.

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Neuromodulator

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If a neurocrine has a rapid effect it is called a _____.

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Neurotransmitter

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What are Cytokines?

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Cytokines are regulatory peptides that act close to the site where they secreted.

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True or False? Cytokines are stored much like hormones?

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False(Cytokines are produced on demand.)

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True or False? A cytokine can act as an autocrine and a paracrine.

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-True

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Where are receptor proteins located?

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-Cytosol-Cell membrane-Nucleus

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This type of receptor mimics the effect of the naturally occuring ligand?

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-Agonist

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Are First Messengers Lipophilic or Lipophobic?

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-Lipophilic, they are able to enter the cell.

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Which signal molecule is unable to enter the cell?

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-Lipophobic

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What are the four classes of membrane receptors?

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- Ligand-gated ion channels- Intergrin linked to cytoskeleton- G protein-coupled receptor with

seven membrane- Receptor Enzyme

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What is the result of a ligand binding to a ligand gated channel?

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-Channel opens or closes

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Which type of regulation results in the reduction in the number of receptors and/or binding affinity for the ligand?

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Down-regulation

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What is the result of a ligand binding to a G protein coupled receptor?

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-The G-protein receptor opens an ion channel or alters enzyme activity

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Which membrane receptor results in the activation of an intracellular enzyme?

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-Enzyme receptor

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Which membrane receptor result in a change to the cytoskeleton?

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-Intergrin

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Which of the four categories of membrane receptors do NOT use signal transduction?

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-Ligand gated